Field of the Invention
The invention relates to a method for checking sheets of bills during their production.
The manufacture of bills, in particular bank notes, takes place in known manner in several separate operations, which may be separated by a period of several days or even several weeks and the individual working stations of which may also have different locations. As a rule the manufacture incorporates the following steps: preparation of a stack with a certain number of sheets of securities, printing of these sheets on both sides in several stages with a given number of bill impressions, so called utilities, various quality controls of random sampling nature and a final visual quality control before numbering of the sheets of bills, then printing of the serial numbers in a numbering machine, cutting up the stack of sheets including trimming into bundles of bills, placing bill bands around the bundles of bills, forming blocks of bundles with consecutively numbered bills of a certain series and packing of these blocks of bundles.
Hitherto, substantially two different systems have been available for checking the manufacture of sheets of bills:
(a) the entire manufacture takes place within a locked and supervised area, in which the sheets of notes or securities themselves are not checked in their various stages of manufacture. Monitoring of the area or of the respective manufacturing and processing areas consists of constant checking of incoming and outgoing workers and visitors, of random intermediate checks and of a material balance between the paper in an unprocessed state supplied for manufacture and the output of finished, processed bills.
(b) Within the framework of the other checking system, all sheets of securities are counted daily in the individual stages of manufacture, locked up overnight in a safe and re-issued the next morning or at the time of further processing. In this way, a daily check of the quantity of sheets of bills and bills circulating in manufacturing or of the number of sheets of bills and bills which are in manufacture, is possible.
In both checking systems, the greatest danger lies in the loss of a sheet of bills in the time interval elapsing between the processing of the sheet and the next counting check. This time interval is generally extraordinarily long in the case of the first checking system. Even in the case of the second checking system, the absence of a sheet of bills can only be reliably detected in the evening of a working day. If the manufacture incorporates intaglio printing using intermediate sheets, then due to technical processes, two or more days may elapse until the respective stack of sheets is once more accessible for a counting check.
If the absence of a sheet of bills is ascertained, then generally one can only discover where a sheet was lost or removed, with a great deal of trouble by retracing the preceding working stages. However, frequently it is no longer possible to ascertain with absolute certainty when and where a sheet disappeared from the sequence of operations. Due to the hitherto conventional counting checks of the sheets of a stack, it is also only possible to monitor the exact number, but it is not possible to ascertain whether somewhere in the sequence of operations, a sheet of bills was replaced by another sheet of paper, either by error or with intent to defraud.